Read input data into a compute shader in URP

1. Create a graphics buffer using

   CreateBuffer

   , then add a handle to it in your pass data. For example:

   // Declare a buffer handleBufferHandle m_InputBufferHandle;// Add the handle to your pass dataclass PassData{    public BufferHandle input;    // ...}// Create the buffer in RecordRenderGraphpublic override void RecordRenderGraph(RenderGraph renderGraph, ContextContainer frameData){    // Create the input buffer as a structured buffer of 20 ints    BufferDesc desc = new BufferDesc    {        name   = "InputBuffer",        count  = 20,        stride = sizeof(int),        target = GraphicsBuffer.Target.Structured    };    m_InputBufferHandle = renderGraph.CreateBuffer(desc);}

2. Create placeholder data in the buffer to read from for this example:

   // Placeholder input data for the compute shaderprivate List<int> inputData = new List<int>();// Initialize in the render pass constructorpublic ComputePass(){    for (int i = 0; i < 20; i++)    {        inputData.Add(i);    }}

3. Attach the buffer handle and data to the pass data.

   using (var builder = renderGraph.AddComputePass("ComputePass", out PassData passData)){    passData.input = m_InputBufferHandle;    passData.bufferData = inputData;}

4. Use the

   UseBuffer

   method to declare the buffer as an input of this pass in the render graph system. For example:

   builder.UseBuffer(passData.input, AccessFlags.Read);

5. In your

   SetRenderFunc

   method, use the

   SetBufferData

   API to upload the input data to the buffer and the

   SetComputeBufferParam

   API to attach the buffer to the compute shader. For example:

   // Upload input data to the Render Graph buffercontext.commandBuffer.SetBufferData(passData.input, passData.bufferData);// Attach buffer to the compute shader// The first parameter is the compute shader// The second parameter is the function that uses the buffer// The third parameter is the RWStructuredBuffer input variable to attach the buffer to// The fourth parameter is the handle to the input buffercontext.commandBuffer.SetComputeBufferParam(passData.computeShader, passData.computeShader.FindKernel("Main"), "inputData", passData.input);

Example

Additional resources

• Compute shaders
• Writing shaders
• Write to and read from a compute shader in a render pass